Tag Archives: Speed

With many people being forced to work from home, there’s increased load on consumer ISPs. You may be asking yourself: how well is my ISP performing with even more traffic? Today we’re announcing the general availability of speed.cloudflare.com, a way to gain meaningful insights into exactly how well your network is performing.

Although there are a slew of speed testing tools out there, none of them give you precise insights into how they came to those measurements and how they map to real-world performance. With speed.cloudflare.com, we give you insights into what we’re measuring and how exactly we calculate the scores for your network connection. Best of all, you can easily download the measurements from right inside the tool if you’d like to perform your own analysis.

We also know you care about privacy. We believe that you should know what happens with the results generated by this tool. Many other tools sell the data to third parties. Cloudflare does not sell your data. Performance data is collected and anonymized and is governed by the terms of our Privacy Policy. The data is used anonymously to determine how we can improve our network, both in terms of capacity as well as to help us determine which Internet Service Providers to peer with.

The test has three main components: download, upload and a latency test. Each measures different aspects of your network connection.

Down

For starters we run you through a basic download test. We start off downloading small files and progressively move up to larger and larger files until the test has saturated your Internet downlink. Small files (we start off with 10KB, then 100KB and so on) are a good representation of how websites will load, as these typically encompass many small files such as images, CSS stylesheets and JSON blobs.

For each file size, we show you the measurements inside a table, allowing you to drill down. Each dot in the bar graph represents one of the measurements, with the thin line delineating the range of speeds we’ve measured. The slightly thicker block represents the set of measurements between the 25th and 75th percentile.

Getting up to the larger file sizes we can see true maximum throughput: how much bandwidth do you really have? You may be wondering why we have to use progressively larger files. The reason is that download speeds start off slow (this is aptly called slow start) and then progressively gets faster. If we were to use only small files we would never get to the maximum throughput that your network provider supports, which should be close to the Internet speed your ISP quoted you when you signed up for service.

The maximum throughput on larger files will be indicative of how fast you can download large files such as games (GTA V is almost 100 GB to download!) or the maximum quality that you can stream video on (lower download speed means you have to use a lower resolution to get continuous playback). We only increase download file sizes up to the absolute minimum required to get accurate measurements: no wasted bandwidth.

Up

Upload is the opposite of download: we send data from your browser to the Internet. This metric is more important nowadays with many people working from home: it directly affects live video conferencing. A faster upload speed means your microphone and video feed can be of higher quality, meaning people can see and hear you more clearly on videoconferences.

Measurements for upload operate in the same manner: we progressively try to upload larger and larger files up until the point we notice your connection is saturated.

Speed measurements are never 100% consistent, which is why we repeat them. An easy way for us to report your speed would be to simply report the fastest speed we see. The problem is that this will not be representative of your real-world experience: latency and packet loss constantly fluctuates, meaning you can’t expect to see your maximum measured performance all the time.

To compensate for this, we take the 90th percentile of measurements, or p90 and report that instead of the absolute maximum speed that we measured. Taking the 90th percentile is a more accurate representation in that it discounts peak outliers, which is a much closer approximation of what you can expect in terms of speeds in the real world.

Latency and Jitter

Download and upload are important metrics but don’t paint the entire picture of the quality of your Internet connection. Many of us find ourselves interacting with work and friends over videoconferencing software more than ever. Although speeds matter, video is also very sensitive to the latency of your Internet connection. Latency represents the time an IP packet needs to travel from your device to the service you’re using on the Internet and back. High latency means that when you’re talking on a video conference, it will take longer for the other party to hear your voice.

But, latency only paints half the picture. Imagine yourself in a conversation where you have some delay before you hear what the other person says. That may be annoying but after a while you get used to it. What would be even worse is if the delay differed constantly: sometimes the audio is almost in sync and sometimes it has a delay of a few seconds. You can imagine how often this would result into two people starting to talk at the same time. This is directly related to how stable your latency is and is represented by the jitter metric. Jitter is the average variation found in consecutive latency measurements. A lower number means that the latencies measured are more consistent, meaning your media streams will have the same delay throughout the session.

We’ve designed speed.cloudflare.com to be as transparent as possible: you can click into any of the measurements to see the average, median, minimum, maximum measurements, and more. If you’re interested in playing around with the numbers, there’s a download button that will give you the raw results we measured.

The entire speed.cloudflare.com backend runs on Workers, meaning all logic runs entirely on the Cloudflare edge and your browser, no server necessary! If you’re interested in seeing how the benchmarks take place, we’ve open-sourced the code, feel free to take a peek on our Github repository.

We hope you’ll enjoy adding this tool to your set of network debugging tools. We love being transparent and our tools reflect this: your network performance is more than just one number. Give it a whirl and let us know what you think.

Have you ever wanted to quickly test a new performance idea, or see if the latest performance wisdom is beneficial to your site? As web performance appears to be a stochastic process, it is really important to be able to iterate quickly and review the effects of different experiments. The challenge is to be able to arbitrarily change requests and responses without the overhead of setting up another internet facing server. This can be straightforward to implement by combining two of my favourite technologies : WebPageTest and Cloudflare Workers. Pat Meenan sums this up with the following slide from a recent getting the most of WebPageTest presentation:

So what is Cloudflare Workers and why is it ideally suited to easy prototyping of optimizations?

Cloudflare Workers

From the documentation :

Cloudflare Workers provides a lightweight JavaScript execution environment that allows developers to augment existing applications or create entirely new ones without configuring or maintaining infrastructure.A Cloudflare Worker is a programmable proxy which brings the simplicity and flexibility of the Service Workers event-based fetch API from the browser to the edge. This allows a worker to intercept and modify requests and responses.

With the Service Worker API you can add an EventListener to any fetch event that is routed through the worker script and modify the request to come from a different origin.

Cloudflare Workers also provides a streaming HTMLRewriter to enable on the fly modification of HTML as it passes through the worker. The streaming nature of this parser ensures latency is minimised as the entire HTML document does not have to be buffered before rewriting can happen.

Setting up a worker

It is really quick and easy to sign up for a free subdomain at workers.dev which provides you with 100,000 free requests per day. There is a quick-start guide available here.To be able to run the examples in this post you will need to install Wrangler, the CLI tool for deploying workers. Once Wrangler is installed run the following command to download the example worker project:

wrangler generate wpt-proxy https://github.com/xtuc/WebPageTest-proxy

You will then need to update the wrangler.toml with your account_id, which can be found in the dashboard in the right sidebar. Then configure an API key with the command:

wrangler config

Finally, you can publish the worker with:

wrangler publish

At this the point, the worker will be active at

https://wpt-proxy.<your-subdomain>.workers.dev.

WebPageTest OverrideHost

Now that your worker is configured, the next step is to configure WebPageTest to redirect requests through the worker. WebPageTest has a feature where it can re-point arbitrary origins to a different domain. To access the feature in WebPageTest, you need to use the WebPageTest scripting language “overrideHost” command, as shown:

This example will redirect all network requests to www.bbc.co.uk to wpt-proxy.prf.workers.dev instead. WebPageTest also adds an x-host header to each redirected request so that the destination can determine for which host the request was originally intended:

x-host: www.bbc.co.uk

The script can process multiple overrideHost commands to override multiple different origins. If HTTPS is used, WebPageTest can use HTTP/2 and benefit from connection coalescing:

The potential performance improvement of loading a page over a single connection, eliminating the additional DNS lookup, TCP connection and TLS handshakes, can be seen by comparing the filmstrips and waterfalls. There are several reasons why you may not want or be able to move everything to a single domain, but at least it is now easy to see what the performance difference would be.

HTMLRewriter

With the HTMLRewriter, it is possible to change the HTML response as it passes through the worker. A jQuery-like syntax provides CSS-selector matching and a standard set of DOM mutation methods. For instance you could rewrite your page to measure the effects of different preload/prefetch strategies, review the performance savings of removing or using different third-party scripts, or you could stock-take the HEAD of your document. One piece of performance advice is to self-host some third-party scripts. This example script invokes the HTMLRewriter to listen for a script tag with a src attribute. If the script is from a proxiable domain the src is rewritten to be first-party, with a specific path prefix.

HTTP/2 prioritization

What if you want to see what the effect of changing the HTTP/2 prioritization of assets would make to your website? Cloudflare Workers provide custom http2 prioritization schemes that can be applied by setting a custom header on the response. The cf-priority header is defined as <priority>/<concurrency> so adding:

response.headers.set('cf-priority', “30/0”);

would set the priority of that response to 30 with a concurrency of 0 for the given response. Similarly, “30/1” would set concurrency to 1 and “30/n” would set concurrency to n. With this flexibility, you can prioritize the bytes that are important for your website or run a bulk test to prove that your new prioritization scheme is better than any of the existing browser implementations.

Summary

A major barrier to understanding and innovation, is the amount of time is takes to get feedback. Having a quick and easy framework, to try out a new idea and comprehend the impact, is key. I hope this post has convinced you that combining WebPageTest and Cloudflare Workers is an easy solution to this problem and is indeed magic

Congratulations on making it through Speed Week. In the last week, Cloudflare has: described how our global network speeds up the Internet, launched a HTTP/2 prioritisation model that will improve web experiences on all browsers, launched an image resizing service which will deliver the optimal image to every device, optimized live video delivery, detailed how to stream progressive images so that they render twice as fast – using the flexibility of our new HTTP/2 prioritisation model and finally, prototyped a new over-the-wire format for JavaScript that could improve application start-up performance especially on mobile devices. As a bonus, we’re also rolling out one more new feature: “TCP Turbo” automatically chooses the TCP settings to further accelerate your website.

As a company, we want to help every one of our customers improve web experiences. The growth of Cloudflare, along with the increase in features, has often made simple questions difficult to answer:

How fast is my website?

How should I be thinking about performance features?

How much faster would the site be if I were to enable a particular feature?

This post will describe the exciting changes we have made to the Speed Page on the Cloudflare dashboard to give our customers a much clearer understanding of how their websites are performing and how they can be made even faster. The new Speed Page consists of :

A visual comparison of your website loading on Cloudflare, with caching enabled, compared to connecting directly to the origin.

The measured improvement expected if any performance feature is enabled.

A report describing how fast your website is on desktop and mobile.

We want to simplify the complexity of making web experiences fast and give our customers control. Take a look – We hope you like it.

Why do fast web experiences matter?

Customer experience : No one likes slow service. Imagine if you go to a restaurant and the service is slow, especially when you arrive; you are not likely to go back or recommend it to your friends. It turns out the web works in the same way and Internet customers are even more demanding. As many as 79% of customers who are “dissatisfied” with a website’s performance are less likely to buy from that site again.

Engagement and Revenue : There are many studies explaining how speed affects customer engagement, bounce rates and revenue.

Reputation : There is also brand reputation to consider as customers associate an online experience to the brand. A study found that for 66% of the sample website performance influences their impression of the company.

Diversity : Mobile traffic has grown to be larger than its desktop counterpart over the last few years. Mobile customers’ expectations have becoming increasingly demanding and expect seamless Internet access regardless of location.

Mobile provides a new set of challenges that includes the diversity of device specifications. When testing, be aware that the average mobile device is significantly less capable than the top-of-the-range models. For example, there can be orders-of-magnitude disparity in the time different mobile devices take to run JavaScript. Another challenge is the variance in mobile performance, as customers move from a strong, high quality office network to mobile networks of different speeds (3G/5G), and quality within the same browsing session.

New Speed Page

There is compelling evidence that a faster web experience is important for anyone online. Most of the major studies involve the largest tech companies, who have whole teams dedicated to measuring and improving web experiences for their own services. At Cloudflare we are on a mission to help build a better and faster Internet for everyone – not just the selected few.

Delivering fast web experiences is not a simple matter. That much is clear.To know what to send and when requires a deep understanding of every layer of the stack, from TCP tuning, protocol level prioritisation, content delivery formats through to the intricate mechanics of browser rendering. You will also need a global network that strives to be within 10 ms of every Internet user. The intrinsic value of such a network, should be clear to everyone. Cloudflare has this network, but it also offers many additional performance features.

With the Speed Page redesign, we are emphasizing the performance benefits of using Cloudflare and the additional improvements possible from our features.

The de facto standard for measuring website performance has been WebPageTest. Having its creator in-house at Cloudflare encouraged us to use it as the basis for website performance measurement. So, what is the easiest way to understand how a web page loads? A list of statistics do not paint a full picture of actual user experience. One of the cool features of WebPageTest is that it can generate a filmstrip of screen snapshots taken during a web page load, enabling us to quantify how a page loads, visually. This view makes it significantly easier to determine how long the page is blank for, and how long it takes for the most important content to render. Being able to look at the results in this way, provides the ability to empathise with the user.

How fast on Cloudflare ?

After moving your website to Cloudflare, you may have asked: How fast did this decision make my website? Well, now we provide the answer:

Comparison of website performance using Cloudflare.

As well as the increase in speed, we provide filmstrips of before and after, so that it is easy to compare and understand how differently a user will experience the website. If our tests are unable to reach your origin and you are already setup on Cloudflare, we will test with development mode enabled, which disables caching and minification.

Site performance statistics

How can we measure the user experience of a website?

Traditionally, page load was the important metric. Page load is a technical measurement used by browser vendors that has no bearing on the presentation or usability of a page. The metric reports on how long it takes not only to load the important content but also all of the 3rd party content (social network widgets, advertising, tracking scripts etc.). A user may very well not see anything until after all the page content has loaded, or they may be able to interact with a page immediately, while content continues to load.

A user will not decide whether a page is fast by a single measure or moment. A user will perceive how fast a website is from a combination of factors:

when they see any response

when they see the content they expect

when they can interact with the page

when they can perform the task they intended

Experience has shown that if you focus on one measure, it will likely be to the detriment of the others.

Importance of Visual response

If an impatient user navigates to your site and sees no content for several seconds or no valuable content, they are likely to get frustrated and leave. The paint timing spec defines a set of paint metrics, when content appears on a page, to measure the key moments in how a user perceives performance.

First Contentful Paint (FCP) is the time when the browser first renders any DOM content.

First Meaningful Paint (FMP) is the point in time when the page’s “primary” content appears on the screen. This metric should relate to what the user has come to the site to see and is designed as the point in time when the largest visible layout change happens.

Speed Index attempts to quantify the value of the filmstrip rather than using a single paint timing. The speed index measures the rate at which content is displayed – essentially the area above the curve. In the chart below from our progressive image feature you can see reaching 80% happens much earlier for the parallelized (red) load rather than the regular (blue).

Importance of interactivity

The same impatient user is now happy that the content they want to see has appeared. They will still become frustrated if they are unable to interact with the site. Time to Interactive is the time it takes for content to be rendered and the page is ready to receive input from the user. Technically this is defined as when the browser’s main processing thread has been idle for several seconds after first meaningful paint.

The Speed Tab displays these key metrics for mobile and desktop.

How much faster on Cloudflare ?

The Cloudflare Dashboard provides a list of performance features which can, admittedly, be both confusing and daunting. What would be the benefit of turning on Rocket Loader and on which performance metrics will it have the most impact ? If you upgrade to Pro what will be the value of the enhanced HTTP/2 prioritisation ? The optimization section answers these questions.

Tests are run with each performance feature turned on and off. The values for the tests for the appropriate performance metrics are displayed, along with the improvement. You can enable or upgrade the feature from this view. Here are a few examples :

If Rocket Loader were enabled for this website, the render-blocking JavaScript would be deferred causing first paint time to drop from 1.25s to 0.81s – an improvement of 32% on desktop.

Image heavy sites do not perform well on slow mobile connections. If you enable Mirage, your customers on 3G connections would see meaningful content 1s sooner – an improvement of 29.4%.

So how about our new features?

We tested the enhanced HTTP/2 prioritisation feature on an Edge browser on desktop and saw meaningful content display 2s sooner – an improvement of 64%.

This is a more interesting result taken from the blog example used to illustrate the progressive image streaming. At first glance the improvement of 29% in speed index is good. The filmstrip comparison shows a more significant difference. In this case the page with no images shown is already 43% visually complete for both scenarios after 1.5s. At 2.5s the difference is 77% compared to 50%.

This is a great example of how metrics do not tell the full story. They cannot completely replace viewing the page loading flow and understanding what is important for your site.

How to try

This is our first iteration of the new Speed Page and we are eager to get your feedback. We will be rolling this out to beta customers who are interested in seeing how their sites perform. To be added to the queue for activation of the new Speed Page please click on the banner on the overview page,

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